diff options
Diffstat (limited to 'src/scanline_effect.c')
| -rw-r--r-- | src/scanline_effect.c | 261 |
1 files changed, 261 insertions, 0 deletions
diff --git a/src/scanline_effect.c b/src/scanline_effect.c new file mode 100644 index 000000000..b4de0689f --- /dev/null +++ b/src/scanline_effect.c @@ -0,0 +1,261 @@ +#include "global.h" +#include "data2.h" +#include "task.h" +#include "trig.h" +#include "scanline_effect.h" + +static void CopyValue16Bit(void); +static void CopyValue32Bit(void); + +extern u16 gBattle_BG0_Y; +extern u16 gBattle_BG0_X; +extern u16 gBattle_BG1_X; +extern u16 gBattle_BG1_Y; +extern u16 gBattle_BG2_X; +extern u16 gBattle_BG2_Y; +extern u16 gBattle_BG3_X; +extern u16 gBattle_BG3_Y; + +EWRAM_DATA static u8 sShouldStopWaveTask = FALSE; + +struct ScanlineEffect gScanlineEffect; + +// Per-scanline register values. +// This is double buffered so that it can be safely written to at any time +// without overwriting the buffer that the DMA is currently reading +u16 gScanlineEffectRegBuffers[2][0x3C0]; + +void ScanlineEffect_Stop(void) +{ + gScanlineEffect.state = 0; + DmaStop(0); + if (gScanlineEffect.waveTaskId != 0xFF) + { + DestroyTask(gScanlineEffect.waveTaskId); + gScanlineEffect.waveTaskId = 0xFF; + } +} + +void ScanlineEffect_Clear(void) +{ + CpuFill16(0, gScanlineEffectRegBuffers, sizeof(gScanlineEffectRegBuffers)); + gScanlineEffect.dmaSrcBuffers[0] = NULL; + gScanlineEffect.dmaSrcBuffers[1] = NULL; + gScanlineEffect.dmaDest = NULL; + gScanlineEffect.dmaControl = 0; + gScanlineEffect.srcBuffer = 0; + gScanlineEffect.state = 0; + gScanlineEffect.unused16 = 0; + gScanlineEffect.unused17 = 0; + gScanlineEffect.waveTaskId = 0xFF; +} + +void ScanlineEffect_SetParams(struct ScanlineEffectParams params) +{ + if (params.dmaControl == SCANLINE_EFFECT_DMACNT_16BIT) // 16-bit + { + // Set the DMA src to the value for the second scanline because the + // first DMA transfer occurs in HBlank *after* the first scanline is drawn + gScanlineEffect.dmaSrcBuffers[0] = (u16 *)gScanlineEffectRegBuffers[0] + 1; + gScanlineEffect.dmaSrcBuffers[1] = (u16 *)gScanlineEffectRegBuffers[1] + 1; + gScanlineEffect.setFirstScanlineReg = CopyValue16Bit; + } + else // assume 32-bit + { + // Set the DMA src to the value for the second scanline because the + // first DMA transfer occurs in HBlank *after* the first scanline is drawn + gScanlineEffect.dmaSrcBuffers[0] = (u32 *)gScanlineEffectRegBuffers[0] + 1; + gScanlineEffect.dmaSrcBuffers[1] = (u32 *)gScanlineEffectRegBuffers[1] + 1; + gScanlineEffect.setFirstScanlineReg = CopyValue32Bit; + } + + gScanlineEffect.dmaControl = params.dmaControl; + gScanlineEffect.dmaDest = params.dmaDest; + gScanlineEffect.state = params.initState; + gScanlineEffect.unused16 = params.unused9; + gScanlineEffect.unused17 = params.unused9; +} + +void ScanlineEffect_InitHBlankDmaTransfer(void) +{ + if (gScanlineEffect.state == 0) + { + return; + } + else if (gScanlineEffect.state == 3) + { + gScanlineEffect.state = 0; + DmaStop(0); + sShouldStopWaveTask = TRUE; + } + else + { + DmaStop(0); + // Set DMA to copy to dest register on each HBlank for the next frame. + // The HBlank DMA transfers do not occurr during VBlank, so the transfer + // will begin on the HBlank after the first scanline + DmaSet(0, gScanlineEffect.dmaSrcBuffers[gScanlineEffect.srcBuffer], gScanlineEffect.dmaDest, gScanlineEffect.dmaControl); + // Manually set the reg for the first scanline + gScanlineEffect.setFirstScanlineReg(); + // Swap current buffer + gScanlineEffect.srcBuffer ^= 1; + } +} + +// These two functions are used to copy the register for the first scanline, +// depending whether it is a 16-bit register or a 32-bit register. + +static void CopyValue16Bit(void) +{ + u16 *dest = (u16 *)gScanlineEffect.dmaDest; + u16 *src = (u16 *)&gScanlineEffectRegBuffers[gScanlineEffect.srcBuffer]; + + *dest = *src; +} + +static void CopyValue32Bit(void) +{ + u32 *dest = (u32 *)gScanlineEffect.dmaDest; + u32 *src = (u32 *)&gScanlineEffectRegBuffers[gScanlineEffect.srcBuffer]; + + *dest = *src; +} + +#define tStartLine data[0] +#define tEndLine data[1] +#define tWaveLength data[2] +#define tSrcBufferOffset data[3] +#define tFramesUntilMove data[4] +#define tDelayInterval data[5] +#define tRegOffset data[6] +#define tApplyBattleBgOffsets data[7] + +static void TaskFunc_UpdateWavePerFrame(u8 taskId) +{ + int value = 0; + int i; + int offset; + + if (sShouldStopWaveTask) + { + DestroyTask(taskId); + gScanlineEffect.waveTaskId = 0xFF; + } + else + { + if (gTasks[taskId].tApplyBattleBgOffsets) + { + switch (gTasks[taskId].tRegOffset) + { + case SCANLINE_EFFECT_REG_BG0HOFS: + value = gBattle_BG0_X; + break; + case SCANLINE_EFFECT_REG_BG0VOFS: + value = gBattle_BG0_Y; + break; + case SCANLINE_EFFECT_REG_BG1HOFS: + value = gBattle_BG1_X; + break; + case SCANLINE_EFFECT_REG_BG1VOFS: + value = gBattle_BG1_Y; + break; + case SCANLINE_EFFECT_REG_BG2HOFS: + value = gBattle_BG2_X; + break; + case SCANLINE_EFFECT_REG_BG2VOFS: + value = gBattle_BG2_Y; + break; + case SCANLINE_EFFECT_REG_BG3HOFS: + value = gBattle_BG3_X; + break; + case SCANLINE_EFFECT_REG_BG3VOFS: + value = gBattle_BG3_Y; + break; + } + } + if (gTasks[taskId].tFramesUntilMove != 0) + { + gTasks[taskId].tFramesUntilMove--; + offset = gTasks[taskId].tSrcBufferOffset + 320; + for (i = gTasks[taskId].tStartLine; i < gTasks[taskId].tEndLine; i++) + { + gScanlineEffectRegBuffers[gScanlineEffect.srcBuffer][i] = gScanlineEffectRegBuffers[0][offset] + value; + offset++; + } + } + else + { + gTasks[taskId].tFramesUntilMove = gTasks[taskId].tDelayInterval; + offset = gTasks[taskId].tSrcBufferOffset + 320; + for (i = gTasks[taskId].tStartLine; i < gTasks[taskId].tEndLine; i++) + { + gScanlineEffectRegBuffers[gScanlineEffect.srcBuffer][i] = gScanlineEffectRegBuffers[0][offset] + value; + offset++; + } + + // increment src buffer offset + gTasks[taskId].tSrcBufferOffset++; + if (gTasks[taskId].tSrcBufferOffset == gTasks[taskId].tWaveLength) + gTasks[taskId].tSrcBufferOffset = 0; + } + } +} + +static void GenerateWave(u16 *buffer, u8 frequency, u8 amplitude, u8 unused) +{ + u16 i = 0; + u8 theta = 0; + + while (i < 256) + { + buffer[i] = (gSineTable[theta] * amplitude) / 256; + theta += frequency; + i++; + } +} + +// Initializes a background "wave" effect that affects scanlines startLine (inclusive) to endLine (exclusive). +// 'frequency' and 'amplitude' control the frequency and amplitude of the wave. +// 'delayInterval' controls how fast the wave travels up the screen. The wave will shift upwards one scanline every 'delayInterval'+1 frames. +// 'regOffset' is the offset of the video register to modify. +u8 ScanlineEffect_InitWave(u8 startLine, u8 endLine, u8 frequency, u8 amplitude, u8 delayInterval, u8 regOffset, bool8 applyBattleBgOffsets) +{ + int i; + int offset; + struct ScanlineEffectParams params; + u8 taskId; + + ScanlineEffect_Clear(); + + params.dmaDest = (void *)(REG_ADDR_BG0HOFS + regOffset); + params.dmaControl = SCANLINE_EFFECT_DMACNT_16BIT; + params.initState = 1; + params.unused9 = 0; + ScanlineEffect_SetParams(params); + + taskId = CreateTask(TaskFunc_UpdateWavePerFrame, 0); + + gTasks[taskId].tStartLine = startLine; + gTasks[taskId].tEndLine = endLine; + gTasks[taskId].tWaveLength = 256 / frequency; + gTasks[taskId].tSrcBufferOffset = 0; + gTasks[taskId].tFramesUntilMove = delayInterval; + gTasks[taskId].tDelayInterval = delayInterval; + gTasks[taskId].tRegOffset = regOffset; + gTasks[taskId].tApplyBattleBgOffsets = applyBattleBgOffsets; + + gScanlineEffect.waveTaskId = taskId; + sShouldStopWaveTask = FALSE; + + GenerateWave(&gScanlineEffectRegBuffers[0][320], frequency, amplitude, endLine - startLine); + + offset = 320; + for (i = startLine; i < endLine; i++) + { + gScanlineEffectRegBuffers[0][i] = gScanlineEffectRegBuffers[0][offset]; + gScanlineEffectRegBuffers[1][i] = gScanlineEffectRegBuffers[0][offset]; + offset++; + } + + return taskId; +} |